Apparatus for treating continuous length webs comprising high velocity gas jets



E. C. BROWN Aug. 10, 1965 APPARATUS FOR TREATING CONTINUOUS LENGTH WEBSCOMPRISING HIGH VELOCITY GAS JETS 2 Sheets-Sheet 1 Filed April 5, 1962Aug. 10, 1965 APPAR Filed April 3, 1962 E. c. BROWN 3,199,224 ATUS FORTREATING CONTINUOUS LEN WEBS COMPRISING HIGH VELOCITY GAS JE 2Sheets-Sheet 2 United States Patent APPARATUS 58R TREATENQ 0NTENUUSLENGTH WEES (IGR ERBENG HlGH VELOC- Ernest C. rown, Danvers, Mass,assignor to Wolverine Equipment (39., Carnhridge, Mass, a corporation ofMassachusetts Filed Apr. 3, W62, Ser. No. 18 15799 3 Qlairns. (ill.34-156) This invention relates to apparatus for treating webs for heattransfer purposes or for causing chemical reactions therein, as intreating webs coated or impregnated with thermosetting or polymerizableplastic or resinous compounds, for example, in the manufacture ofbattery separator webs or the preheating of resin-impregnated papers inpreparation for pleating, as in the manufacture of filters, and to themethod of handling such webs exemplified in the use of such apparatus.

The dryin or setting-up treatment of webs which have coating orimpregnating materials applied to both sides thereof presents certainproblems with respect to uniformity of treatment. If one side is firstcoated and treated, and then the other side, the first coating tends tobe overtreated during exposure of the coating on the second side in thesubsequent treatment. If both sides are treated simultaneously, handlingproblems arise. If conveyors are utilized, even of the open-mesh type,the conveyor tends to mar the coating or to shield the supportingsurface of the web from direct and equal treatment with other portionsof the web, or both. Where continuous processing of such webs isdesired, it has hence been necessary to resort to the use of costlyapparatus adjuncts, for example, tenters or other tensioning devices, tohold both surfaces of the web out of contact with the elements of thedrying or treating apparatus. As the width of the material increases andits tensile strength decreases, such tenters and the like have atendency to cause ruptures or tears if sufiicient tension is applied toprevent the wide webs from contacting portions of the treatingapparatus.

It is a primary object of this invention, therefore, to provide anapparatus for treating relatively wide webs for heat transfer orimpregnant polymerization or the like with the length of the materialbeing treated being unsupported at its sides and under only sufhcienttension to move it forwardly as by pulling one end of the web withfeeder rolls or the like, while providing means for con straining theunsupported length of web being treated to move in a substantiallysingle horizontal plane despite the fact that the pulling tension wouldbe insuificient in and of itself to prevent the moving web from droopingout of a single plane. In this manner, the disadvantages and dangerspresent with the use of cross-tensioning devices, such as tenter frames,and the like are completely avoided.

The objects of the invention are accomplished by utilizing as the heattransfer medium hot air jets which are directed perpendicularly towardsthe web, both from below and from above, and so controlling thegeometry, including the spacing, and the path of flow and the velocityof the air streams that the web floats in a plane substantially midwaybetween the orifices from which the opposed jets originate.

it has heretofore been proposed in Dungler Patent No. 2,682,116 toprovide apparatus wherein side gripping devices convey a tensioned webthrough a dryer having a succession of parallel slits extendingtransversely of the path of the web disposed in alignment above andbelow the web, and between which guide and supporting rollers for theweb are provided. The contact of the latter rollers with the web, inparticular, is detrimental to the most efficient drying operation, andmay be unusable in the case of certain tacky surfaces where the rollerswould tend to remove portions of the impregnant or coating.

The same patentee proposed staggering the slits above and below thepathway so that cloth fed therebetween could assume a wavy appearancewith the air passing directly through a cloth Web into a vacuum arealocated opposite the transverse slit. Such an operation is exceedinglydifficult to control, and of course, should not be utilized in any casewhere such distortion of the web would be harmful to the quality of theproduct. For example, certain material, such as battery separator platematerial, has a stiffness which would prevent its assuming such a wavyappearance without cracking or breaking the brittle material and suchundue flexing and disruption of the impregnant surface coating isobviously undesirable in many other cases.

In accordance with this invention, I produce a floating feed ofuntensioned web through an air dryer, not by staggering parallel fullwidth air streams longitudinally above and below the pathway to createvacuum areas between the orifices, but by directing air towards the webboth from above and below only in discrete areas spaced bothlongitudinally and transversely of the pathway with the air streams inopposed aligned relation. The web is constrained along its length tomove along a substantially plane path because the surfaces of the web asit moves are contacted along selected equal and opposite areas of bothsides thereof with substantially equal volumes of air having little orno velocity but elevated pressure, and along intervening equal andopposite discrete areas segregated both longitudinally and transverselyof the path of movement of said length of material, with substantiallyequal volumes of lower pressure air moving at high velocity normallyinto, along, and substantially normally out of contact with the surfacesof the web between said selected areas.

The building up of a static pressure which is equal on both sides of theweb throughout a matrix is accomplished by providing two opposedapertured plates which lie in planes spaced slightly closer togetherthan the planes of jet nozzles extending into the apertures, and bylocating and shaping exhaust ports in such manner that certain airbetween the exhaust ports remains substantially undisturbed. Por thispurpose the exhaust ports surround the individual nozzles and are soproportioned with respect to the orifices of the nozzles as to exhaustthe gases at approximately the same cubic foot per minute rate as theirrate of issue from the orifices.

Such a construction may be better understood by reference to theaccompanying drawings, illustrating a form of apparatus useful inpractising the method of the invention and in which:

FIG. 1 is :a plan view of such an apparatus;

FIG. 2 is a side elevational view thereof;

FIG. 3 is a cross-sectional view taken along the line 33 of FIG. 1;

FIG. 3a is a cross-sectional detail of a modified form of apparatus;

FIG. 4 is an enlarged cross-sectional detail of a certain part of theapparatus;

FIG. 5 is a representation of the nozzle pattern of the apparatus;

FIG. 6 is still a larger scale depiction of certain portions of theapparatus taken along the line 6-6 of FIG. 5; and

FIG. 7 is an illustrative plan View of a sheet of web material which hasbeen subjected to the operation of the apparatus without being moved inorder to depict the character of the operation as shown by a test to behereinafter described.

The apparatus comprises a lower casing 8 over which is superimposed anupper hood casing 10 which is mounted for restricted movement up anddown towards and away from the lower casing, For this purpose the uppercasing has four threaded brackets 11 which receive supporting shafts 12,all of the shafts 12 being mechanically connectedby sets of miter gears14 to a common adjusting shaft 16 located at the input end of theapparatus. 1

Upper edges of lower casing 8 and lower edges of upper casing 10 are soproportioned that in the position shown there is provided at theleft-hand side of the apparatus aninlet opening 20, and at theright-handside of the apparatus an outlet opening 22 through which openings theweb material may be horizontally passed in flat-wise condition, buttheside edges 21, 21a of the upper casing :and23 of the lower casing are sodesigned as to overlap in telescoping relation to form barriers andsubstantially seal the two casings together along the sides.

As shown in FIG. 3 the upper casing 10 encloses a fan 24 whichleadsthrough controlling dampers 26 and 28 into a plenum 30, and the lowercasing 8 duplicates this construction.

The plenum 30 has as a lower wall a partition plate 32 which isapertured to receive a series of spaced nozzles 40 which extenddownwardly from the plenum 30 in the upper casing and another series 41which extend upwardly from the corresponding plenum 30a in the lowercasing towards apertures located in opposed parallel plates 42 and 44which define the pathway therebetween for the web material W, which maybe fed from a source of supply such as a braked roll (not shown) throughany desired treating station, e.g., a coating operation on both sidesinto inlet 20.

As indicated in FIG. 1 and FIG. 5, all the nozzle are in rows extendingtransversely of the apparatus,'but they are slightly offset from oneanother longitudinally of the apparatus for well-known purposes ofincreasing the uniformity of treatment by assuring that every surfacearea of the length of material being treated is subjected to asubstantially equal volume of high'velocity air.

As shown more particularly in FIG. 6, it will be noted that the nozzles40 terminate in orifices 46 which lie in a single plane, and the nozzles41 in orifices 47, which lie 'in a spaced single plane; and both plates42 and 44 have portions thereof 48 bent upwardly =or dished out of theplanes of the plates to form apertures or exhaust ports 50 of annularshape surrounding each nozzle. The dishing aids in establishing theproper path of air stream flow between the plates. It is further notedthat the orifice planes lie between the planes of the bent-up edges48'forming the exhaust port 50 and the planes of the plates 42 and 44,respectively.

Moreover the area. of the exhaust ports 50 is such that while thevelocity of the air passing therethrough is less than the velocity ofthe air as it emanates from the orifices 46 and 47, substantially thesame volume of air,

per unit of time passes through the exhaust ports as issues from theorifices so that all the air issuing from the orfices is exhaustedthrough the exhaust ports.

, This results in the building up of more or less dead spaces ornon-turbulent zones between the plates 42, 44 in the areas between thebent portions 48, and, as a consequence of the velocity of the airstreams curling around therebetween, as shown by the, arrows in FIG. 6,a static pressure is built up in these areas which, because the areasare equal and opposed on each side of the sheet, tend to stabilize thesheet, despite the impact on and motion of the air streams relative tothe web W in'the discrete areas lying directly opposite the nozzles andtheir surrounding exhaust ports. inner side edges (FIG. 3)'flanged overin telescoping relationship at 56 forming barriers to minimize lateralair flow outwardly of that edge of the Web W, though such inner closurehas not been found to be essential.

The two plates 40 and 42 can have their In any event, it has been foundby demonstration that I in an apparatus of the above character, when theplate a 42 is moved to a proper distance from the plate 44 for a giventype of web material, the web material will be constrained againstdraping o-r drooping or touching either of the plates 42 or :4throughout the length of the dryer, being constrained in a substantiallysingle horizontal path of movement by the air stream. operation in andof itself and without requiring any support at the edges and withoutfluttering at the edges.

The existence of a pressure build-up between the two plates has beendemonstrated by treating aweb without moving it and inserting cinnamonin the air stream. When the material was not moved, it was found that apattern of light and'darkareas developed, as shown in FIG. 7. Thusdirectly beneath ach nozzle there is a separate darkened circularportion 60 where cinnamon was deposited. Surrounding this was a ring 62of very much ligher color, a narrower ring at of darker color, andtherebeyond a matrix 66 of intermediate darlccolor. From this operationit is apparent that drying had advanced in the ring portion 62 to a muchhigher degree than either directly beneath the nozzles in areas 6%? orin the matrix portions oo'surrounding the ring portion.

This is explainable on the ground, as shown in FIG. 6, that the airstream moving with great velocity along the surfaces of the web in areas62 prevents the deposit of cinnamon and develops the greatest dryingpower outwardly from the center of the nozzle, and then reversing andwithdrawing upwardly through the exhaust ports leaves the matrix areasubstantially untreated, because of little or no velocity of the airrelative to the surface of the paper in these areas, as in the areadirectly beheath the nozzles where there is a downward impact but norelative motion along the surface of high velocity air. The ring 64represents an area of cinnamon deposit as the air velocity across thesurface of the sheet decelerates.

This pattern, of course, would not be observable were the material movedcontinuously through the apparatus, because with such continuous motion,each unit area of the product receives equal treatment, and therefore,the entire sheet, as it leaves the apparatus, would be covered uniformlywith cinnamon indicative or uniform treatment throughout both itssurfaces.

As an example, the preheating of phenolformaldehyde resin impregnatedpaper for pleating in the manufacture of automotive oil filters, is bestaccomplished by treating the web on both sides simultaneously with gasesheated to a temperature between F. and250 F. adjusted according to thespeed of motion of the web. This speed will be between the limits of 600ft./ min. and 1000 ft./min. according to the amount of impregnation ofthe paper and the production required.

In this process the paper must become uniformly plastic and malleable sothat it may be formed into pleats in the subsequent pleating apparatus.For this purpose the two plates in the jet preheater are adjusted to adistance of one inch apart. The plates have exhaust ports one andone-quarter inches in diameter, surrounding nozzle orifices five-eighthsinchin diameter, arranged on two and one-half inch centers transverselyandin .row three inches apart longitudinally.

The treating gas in the nozzles has a velocity of 6000 linear ft./min.and the gas passing outward through the exhaust ports has a velocity of2000 linear ft./ min. Under the above described conditions the web ofpaper will be properly softened while it is moving along a substantiallyplane path parallel to and substantially equidistant from the planes ofthe faces of the upper and lower surface plates;

While the apparatus shown in FIGS. 1-3 has a stationary lower casing 8and an upper casing 10 movable relative thereto, in some cases it may bedesirable to make provision for simultaneous equal movement of the upperand lower casings toward and away from each other. This maybe donein avariety of manners, including, for example, the construction shown inEEG. 3a, wherein the lower casing 8, instead of being fixedly supported,is

provided with a series of threaded brackets '70, one of which is shownin FIG. 3, and all of which are in alignment with the up r casingbrackets 11. The brackets 70 are screw threaded with an opposite threadfrom the thread of brackets 11 so that the shafts 12, when rotated, movethe lower casing 8 up or down in counter motion with respect to themotion of the upper casing 10. In this structure the plates 42 and 44will always be equidistant above and below, respectively, the plane of aweb W being fed. into opening at a fixed level.

What is claimed is:

1. Apparatus for treating a flexible continuous web comprising a casingforming a treatin chamber and defining an inlet leading into and adischarge opening leading out of said chamber, two opposed parallelspaced plates extending longitudinally within said casing and f riiingtherebetween a passageway for advance of a web fed into said inletthrough said passageway and out of said discharge opening, said plateshaving opposed aligned apertures dished out of the planes of said platesspaced both longitudinally and transversely of said plates and havingportions between said aligned apertures forming opposed fiat continuousmatrices, opposed aligned nozzles extending into each opposed pair ofapertures leaving annular openings between the nozzles and the apertureedges, through which said annular openings gas emanating from saidnozzles may be exhausted, and the nozzles extending into the aperturesof each plate having orifices lying in a single plane, the distancebetween said orifice planes being at least as great as the minimum distance between said opposed plates whereby upon dis charge of gas at highvelocity through said nozzles, a web advancing through said apparatuswill be contacted along selected equal and opposite areas on both itssides between said matrices with substantially equal volumes 5 as havinglittle or no velocity but elevated pressure and will be contacted alongintervening equal and opposite discrete areas segregated bothlongitudinally and transversely of the path of movement of said web withsubstantially equal volumes of lower pressure gas moving at highvelocity normally into Contact with, along, and substantially normallyout of contact with intervening surfaces of said web lying between saidselected areas to float said advancing web in said passageway free fromcontact with said opposed plates and nozzles.

2. Apparatus as claimed in claim ll, wherein portions of said platesleading to said apertures are bent away from said passageway, and theremainder of said plates forming said matrices lie in parallel planes.

3. Apparatus as claimed in claim 2, wherein the planes if said orificeslie between said parallel plate planes and the edges of said apertures.

References Cited by the Examiner UNITED STATES PATENTS 1,799,375 4/31Jones 34-16 2,042,610 6/36 Littleton 34-160 2,518,268 8/50 Bancroft34-16 2,645,031 7/53 Edwards 34-156 2,742,274 4/56 Edvar 34-1552,780,877 2/57 Warner 34-156 3,012,335 12/61 Allander 34-155 3,041,7397/62 Meier-Windhorst 34-156 3,060,595 10/62 Dapses 34-160 3,070,901 1/63Allander et a1. 34-160 FOREIGN PATENTS 562,354 11/57 Belgium. 639,1835/35 Germany.

OTHER REFERENCES Krantz: (Germany) Patentanmeldung (March 15,

1956), X 20,513, vii/8b (3 pp. spec., 1 sht. dwg.).

NORMAN YUDKOFF, Primary Examiner.

1. APPARATUS FOR TREATING A FLEXIBLE CONTINUOUS WEB COMPRISING A CASINGFORMING A TREATING CHAMBER AND DEFINING AN INLET LEADING INTO AND ADISCHARGE OPENING LEADING OUT OF SAID CHAMBER, TWO OPPOSED PARALLELSPACED PLATES EXTENDING LONGITUDINALLY WITHIN SAID CASING AND FORMINGTHEREBETWEEN A PASSAGEWAY FOR ADVANCE OF A WEB FED INTO SAID INLETTHROUGH SAID PASSAGEWAY AND OUT OF SAID DISCHARGE OPENING, SAID PLATESHAVING OPPOSDED ALIGNED APERTURES DISHED OUT OF THE PLANES OF SAIDPLATES SPACED BOTH LONGITUDINALLY AND TRANSVERSELY OF SAID PLATES ANDHAVING PORTIONS BETWEEN SAID ALIGNED APERTURES FORMING OPPOSED FLATCONTINUOUS MATRICES, OPPOSED ALIGNED NOZZLES EXTENDING INTO EACH OPPOSEDPAIR OF APERTURES LEAVING ANNULAR OPENINGS BETWEEN THE NOZZLES AND THEAPERTURE EDGES, THROUGH WHICH SAID ANNULAR OPENINGS GAS EMANATING FROMSAID NOZZLES MAY BE EXHAUSTED, AND THE NOZZLES EXTENDING INTO THEAPERTURES OF EACH PLATE HAVING ORIFICES LYING IN A SINGLE PLANE, THEDISTANCE BETWEEN SAID ORIFICE PLANES BEING AT LEAST AS GREAT AS THEMINIMUM DISTANCE BETWEEN SAID OPPOSED PLATES WHEREBY UPON DISCHARGE OFGAS AT HIGH VELOCITY THROUGH SAID NOZZLES, A WEB ADVANCING THROUGH SAIDAPPARATUS WILL BE CONTACTED ALONG SELECTED EQUAL AND OPPOSITE AREAS ONBOTH ITS SIDES BETWEEN SAID MATRICES WITH SUBSTANTIALLY EQUAL VOLUMES OFGAS HAVING LITTLE OR NO VELOCITY BUT ELEVATED PRESSURE AND WILL BECONTACTED ALONG INTERVENING EQUAL AND OPPOSITE DISCRETE AREAS SEGREGATEDBOTH LONGITUDINALLY AND TRANSVERSELY OF THE PATH OF MOVEMENT OF SAID WEBWITH SUBSTANTIALLY EQUAL VOLUMES OF LOWER PRESSURE GAS MOVING AT HIGHVELOCITY NORMALLY INTO CONTACT WITH, ALONG, AND SUBSTANTIALLY NORMALLYOUT OF CONTACT WITH INTERVENING SURFACES OF SAID WEB LYING BETWEEN SAIDSELECTED AREAS TO FLOAT SAID ADVANCING WEB IN SAID PASSAGEWAY FREE FROMCONTACT WITH SAID OPPOSED PLATES AND NOZZLES.